1. a) Technical Field of the Invention
The present invention relates to a connection structure for a head tube and a handle securing rod of a bicycle, characterized in that a connection block is secured at a jacket within the head tube, and the center of the connection block is provided with a screw hole, and the head tube is mounted to the connection ring tube of the handle securing rod for the mounting of a securing element to the screw hole of the connection block, and the head tube and the handle securing rod are joined to form as a unit. This will avoid damage caused by friction at the inner wall of the head tube.
2. b) Description of the Prior Art
As shown in FIG. 1, a conventional securing element 1 includes a nut head 11, a screw rod 12, a top block 13, an extension ring 14 and an urging block 15. The bottom side of the top block 13 is an inverted conic shaped ring body. After the screw rod 12 has inserted into the center hole of the top block 13, the top circumferential face of the top block 13 is then screwed at the center hole. The bottom end of the screw rod 12 is an extension from the lower section of the top block 13. The center hole of the extension ring 14 is located near to the conic ring body of the bottom end of the top block 13. The screw rod 12 passes through the top block 13 and the extension ring 14 and is secured at the urging block 15. FIG. 3 shows the mounting of the head tube 2 and the handle securing rod 3 to form as a unit. In this case, the extension from the extension ring 14 causes the head tube 2 and the handle securing rod 3 to mount together so that the end head of the securing rod 3 can be easily provided with a handle. FIG. 4 is another type of conventional securing element 4 including a screw rod 41, a nut ring 42, a spring 43, a pad 44, a ring tube 45, a bottom ring tube 46 and a screw body 47. The circumferential face of the top ring tube 45 has a recessed shape and that of the bottom ring tube 46 is protruded, and the corresponding ends of the two ring tubes 45, 46 have a sloping shape. The screw rod 41 passes through the nut ring 42, the spring 43, the pad 44, the top ring tube 45 and the bottom ring tube 46 in sequence, and then is secured at the screw body 47 to form as a unit. In application, as shown in FIG. 5, when the screw rod 41 rotates, the screw body 47 rotates upward and a pushing force is exerted onto the top ring tube 45 and the bottom ring tube 46. This will cause the corresponding ends to extend radially and the circumferential face urges the tube wall of the head tube 2. As shown in FIG. 6, the end head of the handle-bar securing rod 3 is mounted with the handle.
The drawback of the conventional securing element 1 by means of the radially extended securing element is that the vibration caused by a bumpy road is concentrated at the head tube of the bicycle. The stress thus formed will break the securing element 1 and the tube wall, and the securng effect is inefficient. In some cases, the handle securing rod 3 may be dislocated from the head tube.